Currently, a Long Term Evolution (LTE) system is provided with six standardized LTE system bandwidths, that is, 1.4 megahertz (MHz), 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz. In LTE, user equipment can support 20 MHz. As an actual value of a system bandwidth of a base station changes, the user equipment may absolutely match the system bandwidth of the base station. For example, if the system bandwidth of the base station is 10 MHz, a bandwidth used by the user equipment may be 10 MHz.
When transmitting a channel or a signal to the user equipment, the base station needs to map the channel or the signal to the system bandwidth of the base station, that is, to the bandwidth used by the user equipment, due to a reason that in the LTE system, the system bandwidth of the base station is the same as the bandwidth used by the user equipment. For example, a resource of an uplink/downlink control channel and a resource of a reference signal are separately mapped to the entire system bandwidth of the base station. The control channel may be one or more of a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), a physical hybrid ARQ indicator channel (PHICH), a physical uplink control channel (PUCCH), or a physical random access channel (PRACH). The reference signal may be one or more of a cell-specific reference signal (CRS) or a channel state information-reference signal (CSI-RS). Resources of some channels or signals are dynamically mapped to a designated location of the entire system bandwidth of the base station. The some channels or signals may be one or more of a configured system information block (SIB), a configured random access response (RAR), a configured paging message, or a configured physical downlink shared channel (PDSCH). Resources of other channels or signals are mapped to predefined time-frequency resources of the system bandwidth of the base station. The other channels or signals may be one or more of a primary synchronization signal PSS), a secondary synchronization signal (SSS), or a physical broadcast channel (PBCH).
However, because of spectrum resource division, replanning and redeployment of another system resource, or the like, in an LTE system deployment process, a bandwidth different from the six standardized LTE system bandwidths may be encountered, such as 6 MHz, 6.2 MHz, 6.5 MHz, 7 MHz, 11 MHz, 12 MHz, and 13 MHz. To reduce impact on the user equipment and standardize a bandwidth as far as possible, to adapt to network access capabilities of various user equipments, and to improve utilization of a system resource, a case in which the system bandwidth of the base station does not match the bandwidth of the user equipment potentially exists in the future. For example, the system bandwidth of the base station is 6 MHz, and the bandwidth used by the user equipment is 5 MHz. In this case, in a resource mapping process of the channel or the signal, if determining of an available resource and resource mapping are still performed in ascending order of frequency domains of all physical resource blocks (PRB) in the system bandwidth of the base station, because of a limited bandwidth used by specific user equipment, the user equipment cannot use a resource block beyond a capability of the user equipment or a resource block corresponding to addressing. Therefore, this inflexible resource mapping of the channel or the signal affects normal communication between the base station and the user equipment.